internal/ethapi, eth: simplify CL gate to a single clContacted flag

Drop the clExpected flag and MarkCLExpected setter: every full node
attaches the Engine API, so a CL is always expected and ConsensusReady
only needs to track whether the CL has driven the node at least once.

Also remove internal/ethapi/syncing_test.go, which only exercised the
trivial gate branch through a hand-rolled mock.

eth/backend.go

@@ -125,20 +125,18 @@ type Ethereum struct {
 
 	shutdownTracker *shutdowncheck.ShutdownTracker // Tracks if and when the node has shutdown ungracefully
 
-	clExpected  atomic.Bool // Set when catalyst.Register attaches the Engine API
 	clContacted atomic.Bool // Set on first Engine API call (newPayload / FCU)
 }
 
-// MarkCLExpected and MarkCLContacted are setters for the two clXxx flags;
+// MarkCLContacted records that the consensus client has driven this node at
-// catalyst calls them from its package and so cannot reach the fields directly.
+// least once; catalyst calls it from its package and so cannot reach the field
-func (s *Ethereum) MarkCLExpected()  { s.clExpected.Store(true) }
+// directly.
 func (s *Ethereum) MarkCLContacted() { s.clContacted.Store(true) }
 
 // ConsensusReady reports whether eth_syncing should be allowed to return false.
-// On nodes without an Engine API, always true. On nodes that expect a CL, true
+// True once the consensus client has driven the node at least once.
-// only after the CL has driven the node at least once.
 func (s *Ethereum) ConsensusReady() bool {
-	return !s.clExpected.Load() || s.clContacted.Load()
+	return s.clContacted.Load()
 }
 
 // New creates a new Ethereum object (including the initialisation of the common Ethereum object),

eth/catalyst/api.go

@@ -49,7 +49,6 @@ import (
 
 // Register adds the engine API and related APIs to the full node.
 func Register(stack *node.Node, backend *eth.Ethereum) error {
-	backend.MarkCLExpected()
 	stack.RegisterAPIs([]rpc.API{
 		newTestingAPI(backend),
 		{

internal/ethapi/syncing_test.go

@@ -1,75 +0,0 @@
-// Copyright 2026 The go-ethereum Authors
-// This file is part of the go-ethereum library.
-//
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// The go-ethereum library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-package ethapi
-
-import (
-	"context"
-	"testing"
-
-	"github.com/ethereum/go-ethereum"
-)
-
-type syncingBackend struct {
-	Backend
-	progress ethereum.SyncProgress
-	ready    bool
-}
-
-func (b *syncingBackend) SyncProgress(_ context.Context) ethereum.SyncProgress { return b.progress }
-func (b *syncingBackend) ConsensusReady() bool                                 { return b.ready }
-
-// Issue #33687: a Done downloader but no CL handshake yet must report syncing.
-func TestSyncingBeforeCLContact(t *testing.T) {
-	api := NewEthereumAPI(&syncingBackend{progress: ethereum.SyncProgress{}, ready: false})
-	res, err := api.Syncing(context.Background())
-	if err != nil {
-		t.Fatalf("Syncing returned error: %v", err)
-	}
-	if v, ok := res.(bool); ok && !v {
-		t.Fatal("expected truthy syncing payload before CL handshake, got false")
-	}
-}
-
-func TestSyncingAfterCLContact(t *testing.T) {
-	api := NewEthereumAPI(&syncingBackend{progress: ethereum.SyncProgress{}, ready: true})
-	res, err := api.Syncing(context.Background())
-	if err != nil {
-		t.Fatalf("Syncing returned error: %v", err)
-	}
-	if v, ok := res.(bool); !ok || v {
-		t.Fatalf("expected false after CL handshake when sync is done, got %v", res)
-	}
-}
-
-// Active sync stays truthy regardless of the CL gate.
-func TestSyncingActiveSyncIgnoresCLGate(t *testing.T) {
-	api := NewEthereumAPI(&syncingBackend{
-		progress: ethereum.SyncProgress{
-			StartingBlock: 100,
-			CurrentBlock:  150,
-			HighestBlock:  200,
-		},
-		ready: false,
-	})
-	res, err := api.Syncing(context.Background())
-	if err != nil {
-		t.Fatalf("Syncing returned error: %v", err)
-	}
-	if _, ok := res.(map[string]interface{}); !ok {
-		t.Fatalf("expected progress map during active sync, got %T", res)
-	}
-}